In the present time, compact fluorescent lamps are gaining more and more ground. Their popularity is explained by their significant energy saving and long lives. In order to increase the popularity of compact fluorescent lamps, a design has also been developed that connects the lamp to the lampholder by means of a so-called Edison screw base enabling an easy insertion in the place of conventional incandescent lamps. Previously, the assembling of compact fluorescent lamps with an Edison base was a very laborconsuming process since it required that the lead-in wires for supplying energy to the discharge tube extend from inside the housing and by means of soldering, be connected to the threaded base. Connecting one of the lead-in wires to the central body of the threaded cap could be carried out without any difficulty. It caused, however, a severe problem and also restricted the increase of productivity to fix the other lead-in wire to the sleeve or side portion of the threaded cap.
Several proposed designs aimed at the increase of productivity of compact fluorescent lamps, can lead to the reduction of specific costs which, in turn reduces lamp price and can further accelerate the spread of compact fluorescent lamps. For instance, in U.S. Pat. No. 4,695,767, a compact fluorescent lamp design also suitable for automated assembling is shown. Its principle is that the lead-in wire to be connected to the sleeve surface of the threaded base is directed across the inner hollow of the housing along the cylindrical ring supporting the threaded base to reach the lower edge of the cylindrical ring. Here, around the edge of the cylindrical ring, the lead-in wire is bent backwards along the outer mantle of the cylindrical ring towards the discharge tube. Then, the threaded base is pushed over the cylindrical ring of the housing prepared in the above way wherein the extended lead-in wire is fixed to the housing by way of a friction fit. During tightening, the lead-in wire that has been wedged in between the outer mantle of the cylindrical ring and the inner surface of the sleeve of the threaded base will also achieve electrical contact. This solution is, beyond doubt suitable for decreasing the labor required for assembling. However, it has the disadvantage that the long lead-in wire tends to get damaged or broken as early as during the operations performed prior to assembling with the threaded base.
Its further disadvantage is that it is not easy to handle the long lead-in wire and to direct it exactly and reliably, such handling can only be implemented with the aid of an auxiliary device that increases the expense for an automatic production equipment.
It is also a disadvantage of the above solution that, when connecting the lead-in wire to the threaded base during the operation of pushing on and tightening the threaded base over the cylindrical ring-shaped supporting portion of the housing, the lead-in wire may break or get damaged otherwise leading to the operational failure of the compact fluorescent lamp.